Rivet setting tool

ABSTRACT

A rivet setting tool having a feed mechanism which can be actuated for a rivet setting operation and which imparts an axial movement to a screwthreaded or tensile pin. The feed mechanism comprises a piston cylinder assembly formed by a working piston and a pressing piston. Both pistons are returned to their initial positions by pressure fluid being conducted to the rear sides thereof, thus avoiding the use of return springs acting on the pistons. To provide that effect, a pressure fluid passage extends from the pressure fluid inlet through the handle portion of the tool to a rearward chamber provided behind the working piston and defined at one side thereof by the rearward face of the piston, thereby to urge the working piston towards its initial position, while a further communication urges the pressing piston also towards its initial position.

BACKGROUND OF THE INVENTION

In one form of rivet setting tool for setting screwthreaded rivet nutsor blind rivet nuts, referred to hereinafter for the sake of simplicityas rivet nuts, the tool comprises a forward feed arrangement forimparting an axial movement to the screw-threaded pin or tensile pin,the forward feed arrangement being actuable to perform the rivet nutupsetting operation. The forward feed arrangement comprises a pistoncylinder assembly including a pressing piston and a working piston.

In such a tool, the working movement of the pressing piston and theworking piston is produced by an external compressed air source, whilethe return movement of those pistons is produced by springs. The springsrequired for that purpose are disadvantageous from various points ofview. Apart from the fact that the spring force may gradually becomeweaker due to fatigue in the course of a prolonged period of time or thesprings may even become defective, for example they may break, so thatthe pistons are then no longer satisfactorily returned, there is alsothe problem that springs of suitable quality are very expensive and alsogive rise to further labour costs in assembly of the tool. Furthermore,a spring can only exert a given force so that that consideration alsolimits the speed at which the return movement of the pistons may beeffected.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a rivet setting toolwhich can be produced inexpensively and with a low level of assemblycost.

Another object of the present invention is to provide a rivet settingtool which is comparatively inexpensive but which nonetheless operateswith a high degree of reliability and with a high working speed.

In accordance with the present invention, those and other objects areachieved by a rivet setting tool for setting screw-threaded rivet nutsor blind rivet nuts, comprising a feed means which can be actuated forthe rivet upsetting operation and which imparts an axial movement to thescrewthreaded pin or the tensile pin of the rivet member to be set. Thefeed means comprises a piston-cylinder assembly comprising a pressingpiston and a working piston. The return movement of the pressing pistonand the working piston, after operation of the tool, is produced byconducting the operating pressure fluid of the tool to the rear sides ofthe respective pistons, thus providing for return movement thereofwithout using return springs to produce such movement. Furthermore, apressure fluid passage extends from the pressure fluid inlet means ofthe tool, through the handle portion of the tool, to a rearward chamberwhich is thus disposed at the rearward side of the working piston andwhich is closed off by the rearward face thereof, that is to say, theface of the working piston which is remote from the operating tipportion of the tool where the rivet member to be set is held.

Further objects, features and advantages of a rivet setting tool inaccordance with the present invention will be apparent from thefollowing description of a preferred embodiment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view of a rivet setting tool according to theinvention, in the unactuated condition,

FIG. 2 is a view corresponding to that shown in FIG. 1 of the rivetsetting tool in the actuated condition, and

FIG. 3 is a detail of the structure shown in FIGS. 1 and 2, illustratinga shut-off valve for shutting off the flow of compressed air to the toolwhen it is put down.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring firstly to FIG. 1, shown therein in an unactuated orinoperative condition is a rivet setting tool for setting screwthreadedrivet nuts or blind rivet nuts, comprising a body portion indicatedgenerally by reference numeral 100, and a gripping or handle portion 200which is formed on the body portion 100. At its forward end, to the leftin FIGS. 1 and 2, the body portion 100 comprises a mouthpiece 1.Arranged rearwardly of the mouthpiece 1, that is to say, on the rightthereof as shown in FIGS. 1 and 2, is a clamping chuck comprisingclamping jaws 2 which are surrounded by a conical clamping sleeve 3. Aguide sleeve 4 which is disposed coaxially with the clamping chuck 2, 3is surrounded by a compression coil spring 5. An intermediate portion 6which is also coaxial with the clamping chuck 2, 3 is fixed in positionby means of a lock nut 7.

The whole of the front part of the body portion 100 is enclosed by aforward sleeve portion 8 which is fixed in the housing 101 of the bodyportion 100.

Disposed in the rearward part of the housing 101, which is thus towardsthe right in FIGS. 1 and 2, is an operating or working piston 14 whichis for example a hydraulic piston. On its rearward side, which istowards the right in FIGS. 1 and 2, the working piston 14 defines oneside of a rearward chamber 102 which communicates by way of a recess 103in the housing 101, with a passage or duct 104 which extends in the bodyportion 100 of the tool. Communicating with the passage 104 in the bodyportion 100 is a further duct or passage 205 which extends through thehandle portion 200 and thus runs vertically in for example FIG. 1. Atits lower end, the passage 205 in the handle portion 200 communicateswith a transverse passage 206.

The handle portion 200 carries an actuating member illustrated in theform of a trigger 22 which is movably mounted to the handle portion 200by way of a cylindrical pin 21 acting as a pivot. A lever 24 has one endthereof pivotally connected to the trigger 22 by means of a cylindricalpivot pin 23 while at its other end the lever 24 is connected by meansof a cylindrical pivot pin 25 to a valve pin 26 which is disposed on avalve rod 27. The valve rod 27 extends vertically downwardly in forexample FIG. 1, towards a pressure fluid inlet means as indicated at207.

In its lower portion, the valve rod 27 is provided with a duct orpassage 201 which is in the form of a central bore therein and which atits upper end opens to the exterior laterally at an outlet as indicatedat 202.

An air inlet duct or hose which is not shown in the drawings feedspressure fluid in the form of compressed air into the compressed airinlet means at an air chamber 207 from which the compressed air flowsinto the passage 201 in the valve rod 27, and issues at 202. In thefirst position of the tool as shown in FIG. 1, which is the unactuatedcondition, the outlet 202 of the passage 201 in the valve rod 27 isaligned with the above-mentioned transverse passage 206 communicatingwith the passage 205 in the handle portion 200 so that the compressedair can flow by way of the passage 206 and the passage 104 in the bodyportion 100 into the rearward chamber 102 at the rear of the workingpiston 14. The pressure of the compressed air causes the working piston14 to be moved towards the left in FIG. 1. In addition, the air from thepassage 104 in the body portion 100 flows towards the left in FIG. 1, toa recess or opening 105 in the housing 101 and from there into a suctionchamber 106 and then by way of bores 107 into the interior of the pistonrod 108 which is connected to the working piston 14. There, the airserves for sucking the rivet unless, depending on the designconfiguration of the tool, the operation to be performed is that ofscrewing on a screwthreaded rivet nut.

In addition, the air flowing through the bores 107 in the piston rod 108is available for removing the rivet pins rearwardly through the passage109 which is indicated at the right in FIGS. 1 and 2. The tool alsoincludes an adjusting valve 110 for steplessly adjusting the strength ofthe air flow and thus the force produced by the air, insofar as thevalve 110 can be suitably adjusted by means of a cap nut 20 or anadjusting screw which is not illustrated in the drawings.

In addition, the air flowing through the passage 201 in the valve rod 27flows through a lower transverse passage 209 in the valve rod 27 into apressure chamber 210 associated with a pressing piston 211, the chamber210 being disposed above the pressing piston 211 and thus being disposedat the rear thereof, in the operative direction of movement of thepressing piston 211 which is upwardly in FIGS. 1 and 2. As a result ofthe air flowing into the rearward pressure chamber 210, the piston 211is urged downwardly in FIG. 1. The chamber 212 on the other side of thepiston 211, is relieved through a vent passage 213.

Reference will now be made more specifically to FIG. 2 which shows thesame rivet setting tool as that shown in FIG. 1 so that the samereference numerals are used to denote the same parts. In FIG. 2 howeverthe rivet setting tool is in a second or operated position in which thetrigger 22 has been actuated so that the valve rod 27 is moveddownwardly against the force of a compression spring 38, by way of theinterconnection by means of the lever 24. A comparison between FIGS. 1and 2 will clearly show that pivotal movement of the trigger 22 aboutthe pivot pin 21 causes the lever 24 to move from the inclined positionin FIG. 1 into the substantially vertical position in FIG. 2 in which ittherefore displaces the valve rod 27 downwardly.

By virtue of that movement, a seal 36 carried on the valve rod 27 ismoved away from a housing portion 215 which forms part of the handleportion 200 so that the passage 205 in the handle portion 200 is ventedby way of the bore 216 in which the valve rod 27 is carried and a ventpassage 217 communicating therewith; that also results in venting of therearward chamber 102 which is to the right of the working piston 14, byway of the passage 104 in the body portion 100, the passage 104communicating with the passage 205 in the handle portion 200, asdescribed above.

In addition, a sealing ring 58 which is disposed at the lower end of thevalve rod 27 is moved away from its condition of bearing against aclosure cover 59 so that the compressed air flows from the inlet chamber207 into the front chamber 212 of the pressing piston 211 and thus urgesthe piston 211 upwardly in FIG. 2. As a result of that movement, ahydraulic medium is operative, by way of the pressure passage 120 whichis clearly visible in FIG. 2, to move the working piston 14 towards theright and thus into the position shown in FIG. 2, thereby performing therivet setting operation. After that operation, the trigger 22 isreleased. The compression spring 38 at the bottom of the tool as viewedin FIG. 2 causes the valve rod 27 to be displaced upwardly again wherebythe working piston 14 and the pressing piston 211 return to theirpositions shown in FIG. 1, by the vent bore 217 being closed and thevent bore 213 being opened. It will be seen therefore that theabovedescribed construction provides that the pressing piston 211 andthe working piston 14 are returned to their starting positions for asetting operation by conducting pressure fluid to the rearward sides ofthe respective pistons 211 and 14, that is to say, by conductingpressure fluid into the chambers 210 and 102 respectively. Thatconstruction therefore does not require any return springs actingdirectly on the pistons 211 and 14 to produce the return movementthereof.

Reference will now be made to FIG. 3 showing on an enlarged scale ashut-off or closure valve for automatically interrupting the feed ofcompressed air into the tool, in the position in which the tool has beenset down on a surface on which it is to stand, when the tool is not inoperation.

More specifically therefore, when the rivet setting tool illustrated isput down on to a surface in such a way that it stands on the underneathsurface 60 of its housing, a push rod 61 which projects downwardly outof the underneath surface 60 of the housing is urged inwardly thereof,that is to say upwardly in FIG. 3, and as a result a valve ball disposedin a seating means 62 is pressed against an opening 63 so that the valveball closes the opening 63 and the compressed air can no longer flowinto the tool. That not only avoids unnecessary wastage of compressedair, but it also prevents the compressed air from continuously flowingthrough and out of the tool, as will constantly occur when the tool isin the condition shown in FIG. 1, the air flowing past the adjustingvalve 110 and into the chamber 106. While it might be possible toprevent that flow of compressed air through the tool by closing theadjusting valve 110, it would be disadvantageous constantly to alter apressure setting, once it has been set, by means of the air adjustingscrew member 20, and it would also be much too tedious andtime-consuming constantly to close the rotary valve 110 by way of theadjusting screw member 20, in order to shut off the flow of compressedair. Instead, the valve assembly shown in FIG. 3 provides that the flowof compressed air into and through the tool is shut off practicallyautomatically by way of the actuating push rod 61, when the tool isstood on its surface 60.

It will be appreciated that the above-described embodiment of theapparatus according to the invention has been set forth solely by way ofexample of the principles thereof and that various modifications andalterations may be made therein without thereby departing from thespirit and scope of the invention.

I claim:
 1. A rivet setting tool for setting rivet nuts comprising: atool body including a handle portion; a pressure fluid inlet meansassociated with said handle portion; a forward feed means in said toolbody adapted to be actuated for an upsetting operation and to impart anaxial movement to the rivet pin, including a piston-cylinder meanshaving a pressing piston and a working piston; and means for producingreturn movement of said pistons from the actuated to the rest conditionthereof by conducting pressure fluid to the rear sides thereof,including pressure fluid passage means extending from said pressurefluid inlet means through said handle portion to a rearward chamber atsaid rear side of said working piston in said tool body,a valveactuating rod wherein said pressure fluid passage means comprises afirst portion which passes through said valve rod and a second passageportion in said handle PG,12 portion, said first and second portionscommunicating with each other in a first unactuated position of saidvalve rod, an actuating member connected to said valve rod wherein uponactuation of said actuating member whereby when said valve rod is movedinto a second actuated position a communication is established betweensaid rearward chambers of said working piston and said pressing pistonwith a vent opening.
 2. A tool as set forth in claim 1 wherein in saidfirst position of said valve rod said pressure fluid passage meanscommunicates with a rearward chamber at the rear side of said pressingpiston.
 3. A tool as set forth in claim 1 wherein said pressure fluidpassage means includes a passage portion in said tool body, said passageportion including a valve adapted to communicate a compressed air feedpassage in said body with an annular space therein rearwardly of arivet-clamping chuck means of the tool so that a pin which is torn offin a rivet setting operation is removed from the tool through adischarge passage means.
 4. A rivet setting tool for setting rivet nutscomprising: a tool body including a handle portion; a pressure fluidinlet means associated with said handle portion; a forward feed means insaid tool body adapted to be actuated for an upsetting operation and toimpart an axial movement to the rivet pin, including a piston-cylindermeans having a pressing piston and a working piston; and means forproducing return movement of said pistons from the actuated to the restcondition thereof by conducting pressure fluid to the rear sidesthereof, including pressure fluid passage means extending from saidpressure fluid inlet means through said handle portion to a rearwardchamber at said rear side of said working piston in said toolbody,including a rivet-clamping chuck means aligned with saidpiston-cylinder means, said pressure fluid passage means including apassage portion in said tool body, said passage portion including avalve adapted to communicate a compressed air feed passage in said bodywith an annular space therein rearwardly of said rivet-clamping chuckmeans of the tool so that a pin which is torn off in a rivet settingoperation is removed from the tool through a discharge passage means,said valve is in the form of a rotary valve permitting stepless controlof the force for removing said torn-off rivet pin.
 5. A tool as setforth in claim 1 wherein said rotary valve includes for adjustmentthereof a cap nut embracing the head end of the tool.
 6. A tool as setforth in claim 1 wherein said rotary valve carries an air adjustingscrew.
 7. A rivet setting tool for setting rivet nuts comprising: a toolbody including a handle portion; a pressure fluid inlet means associatedwith said handle portion; a forward feed means in said tool body adaptedto be actuated for an upsetting operation and to impart an axialmovement to the rivet pin, including a piston-cylinder means having apressing piston and a working piston; and means for producing returnmovement of said pistons from the actuated to the rest condition thereofby conducting pressure fluid to the rear sides thereof, includingpressure fluid passage means extending from said pressure fluid inletmeans through said handle portion to a rearward chamber at said rearside of said working piston in said tool body,closure valve meansadapted to automatically interrupt the supply of compressed air to thetool when the tool is set down.
 8. A tool as set forth in claim 1wherein said closure valve means includes an actuating member projectingat the underside of a casing portion enclosing said pressing piston,thereby to actuate said closure valve means for interrupting the supplyof compressed air when the tool is set down on a surface.
 9. A tool asset forth in claim 8 wherein said actuating member is an actuating pushrod.